The MAP test for multimodality

We introduce a test for detecting multimodality in distributions based on minimal constrained spanning trees. We define a Minimal Ascending Path Spanning Tree (MAPST) on a set of points as a spanning tree that has the minimal possible sum of lengths of links with the constraint that starting from any link, the lengths of the links are non-increasing towards a root node. We define similarly MAPSTs with more than one root. We present some algorithms for finding such trees. Based on these trees, we devise a test for multimodality, called the MAP Test (for Minimal Ascending Path). Using simulations, we estimate percentage points of the MAP statistic and assess the power of the test. Finally, we illustrate the use of MAPSTs for determining the number of modes in a distribution of positions of galaxies on photographic plates from a rich galaxy cluster.     

基于映射和二分树的动态查找算法及程序

通过映射构造散列表和二分树,设计一个适用于大规模信息处理的快速动态查找算法,并给出相应程序及其实验结果。     

信阳野生盆景植物的初步观察

记述了信阳野生盆景植物的种类、分布,对该地区野生盆景植物资源的开发利用作了初步探讨     

时变事故树的机理研究及定性分析

本文讨论了时变事故树的表示、化简及定性分析,提出了一种便于计算机处理的化简时变事故树的算法和最小割集的求法,并在理论上给予了证明.该算法对事故树定性分析具有普遍意义.     

Least squares algorithms for constructing constrained ultrametric and additive tree representations of symmetric proximity data

A mathematical programming algorithm is developed for fitting ultrametric or additive trees to proximity data where external constraints are imposed on the topology of the tree. The two procedures minimize a least squares loss function. The method is illustrated on both synthetic and real data. A constrained ultrametric tree analysis was performed on similarities between 32 subjects based on preferences for ten odors, while a constrained additive tree analysis was carried out on some proximity data between kinship terms. Finally, some extensions of the methodology to other tree fitting procedures are mentioned.The first author is supported as Bevoegdverklaard Navorser of the Belgian Nationaal Fonds voor Wetenschappelijk Onderzoek.     

内蒙古草原植物群落分布格局及其主导环境因子解释

基于内蒙古地区草原植物群落样带调查,采用双向指示种分析(TWINSAPN)、除趋势对应分析(DCA)、多元回归树(MRT)和典范对应分析(CCA)等方法,探讨了群落组成、分布格局及影响其分异的主导环境因子.结果如下:1)TWINSPAN将273个群落调查样方划分为8个群系级草原类型,各自代表并反映出该地区草原群落的特点;2)DCA排序结果间接地反映出群落类型与环境梯度之间的关系,CCA排序结果较好地展示了各群落类型中优势物种的生境特征,并进一步展示了该地区草原类型、主要物种与环境因子的响应关系;3)DCA、MRT及CCA结果均表明,气候因素对于该地区草原植被的地域分异影响作用较大,其中水分因子的影响十分突出,特别是最湿月、最暖季节与最冷季节降水,是构成内蒙草原植被类型区域分异的决定性因素;4)MRT与CCA结合使用能进一步挖掘出更多的环境信息,为群落分布格局的形成原因提供更深入更全面的环境解释.     

绿化树移植栽培技术探讨

本文作者紧密结合本地实际和通过多年的林业具体实践取得的工作经验、体会和感受，从规划设计、测量放线、开挖坑穴、移植树种选择及时间、起包运栽、防护措施等六个方面对城乡绿化树木的移植和栽培技术进行了初步探讨和择要介绍，对当前开展的“建生态市、创园林城”活动有一定借鉴和指导意义。     

ECO方法在Fine数中的应用

利用ECO方法研究了Fine数的组合对象,得到了相应的生成规则和生成树.     

油松小卷蛾的监测和综合防治技术

介绍了油松小卷蛾的分布与寄主,阐述了油松小卷蛾的形态特征、生活史及生物学特征,研究了油松小卷蛾的分布规律,讨论了林木受害与林木生长的关系,给出了油松小卷蛾的监测和综合防治技术。     

直径为四的优美树

直径为四的树是否都是优美的，Ｈｕａｎｇ等人认为这个问题是解决优美树猜想的一个关键问题。本文根据树的结构，把直径为四的树分为两种类型，并将其优美性归结为文中定义的蒲公英的优美性。同时证明了两类蒲公英的优美性。